//-----------------------------------------------------------------------------
//
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// Low frequency Honeywell NexWatch tag commands
// PSK1 RF/16, RF/2, 128 bits long (known)
//-----------------------------------------------------------------------------

#include "cmdlfnexwatch.h"

static int CmdHelp(const char *Cmd);

int detectNexWatch(uint8_t *dest, size_t *size, bool *invert) {

	uint8_t preamble[28]   = {0,0,0,0,0,1,0,1,0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
	uint8_t preamble_i[28] = {1,1,1,1,1,0,1,0,1,0,0,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1};
	// sanity check. 
	if ( *size < sizeof(preamble) + 100) return -1;

	size_t startIdx = 0;

	if (!preambleSearch(DemodBuffer, preamble, sizeof(preamble), size, &startIdx)){
		// if didn't find preamble try again inverting
		if (!preambleSearch(DemodBuffer, preamble_i, sizeof(preamble_i), size, &startIdx)) return -4;
		*invert ^= 1;
	}
	
	// size tests?
	return (int) startIdx;
}

int CmdNexWatchDemod(const char *Cmd) {

	if (!PSKDemod("", false)) {
		if (g_debugMode) PrintAndLogEx(DEBUG, "DEBUG: Error - NexWatch can't demod signal");
		return 0;
	}
	bool invert = false;
	size_t size = DemodBufferLen;
	int idx = detectNexWatch(DemodBuffer, &size, &invert);
	if (idx <= 0){
		if (g_debugMode){
			if (idx == -1)
				PrintAndLogEx(DEBUG, "DEBUG: Error - NexWatch not enough samples");
			// else if (idx == -2)
				// PrintAndLogEx(DEBUG, "DEBUG: Error - NexWatch only noise found");
			// else if (idx == -3)
				// PrintAndLogEx(DEBUG, "DEBUG: Error - NexWatch problem during PSK demod");
			else if (idx == -4)
				PrintAndLogEx(DEBUG, "DEBUG: Error - NexWatch preamble not found");
			// else if (idx == -5)
				// PrintAndLogEx(DEBUG, "DEBUG: Error - NexWatch size not correct: %d", size);
			else
				PrintAndLogEx(DEBUG, "DEBUG: Error - NexWatch error %d",idx);
		}
		return 0;
	}
	
	setDemodBuf(DemodBuffer, size, idx+4);
	setClockGrid(g_DemodClock, g_DemodStartIdx + ((idx+4)*g_DemodClock));
	
	idx = 8+32; // 8 = preamble, 32 = reserved bits (always 0)
	
	//get ID
	uint32_t ID = 0;
	for (uint8_t k = 0; k < 4; k++){
		for (uint8_t m = 0; m < 8; m++){
			ID = (ID << 1) | DemodBuffer[m + k + (m*4)];
		}	
	}
	//parity check (TBD)

	//checksum check (TBD)

	//output
	PrintAndLogEx(NORMAL, "NexWatch ID: %d", ID);
	if (invert){
		PrintAndLogEx(NORMAL, "Had to Invert - probably NexKey");
		for (size_t i = 0; i < size; i++)
			DemodBuffer[i] ^= 1;
	} 

	CmdPrintDemodBuff("x");
	return 1;
}

//by marshmellow
//see ASKDemod for what args are accepted
int CmdNexWatchRead(const char *Cmd) {
	lf_read(true, 10000);
	return CmdNexWatchDemod(Cmd);
}

static command_t CommandTable[] = {
	{"help",  CmdHelp,			1, "This help"},
	{"demod", CmdNexWatchDemod,	1, "Demodulate a NexWatch tag (nexkey, quadrakey) from the GraphBuffer"},
	{"read",  CmdNexWatchRead,	0, "Attempt to Read and Extract tag data from the antenna"},
	{NULL, NULL, 0, NULL}
};

int CmdLFNEXWATCH(const char *Cmd) {
	CmdsParse(CommandTable, Cmd);
	return 0;
}

int CmdHelp(const char *Cmd) {
	CmdsHelp(CommandTable);
	return 0;
}
